Waveguide Coupler-Divider for Harmonic Tuning and High Directivity
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Solution Overview
Problem
Waveguide tuners are limited to controlling fundamental frequencies and cannot perform harmonic tuning, and existing directional couplers have limited directivity when used in non-50Ω test environments, affecting the accuracy of microwave transistor testing under controlled impedance conditions.
Innovation Solution
A directional signal coupler-divider is designed using a bi-directional waveguide structure with a secondary waveguide section and strategically placed holes for electromagnetic coupling, allowing for high directivity and the integration of a divided port, enabling accurate harmonic analysis and reduced amplifier power requirements in load pull measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a waveguide tuner is used to control fundamental frequency, then the device structure is simple, but it cannot perform harmonic tuning
Solution Approach 1:
The patent combines a waveguide tuner with a directional coupler into an integrated structure. The coupler is positioned within the waveguide tuner assembly, sharing the same physical space and structural framework. This merging allows the system to achieve both fundamental frequency control and harmonic tuning capability through a single unified device rather than separate components.
Solution Approach 2:
The integrated waveguide tuner-coupler structure serves multiple functions simultaneously: it provides fundamental frequency tuning, harmonic frequency tuning, signal sampling, and impedance measurement. The same physical structure supports both the tuner's impedance transformation function and the coupler's signal sampling function across different frequency harmonics.
2Measurement precision
If existing directional couplers are used in non-50Ω test environments, then the device can operate under various impedance conditions, but the directivity is limited affecting measurement accuracy
Solution Approach 1:
The patent optimizes specific local characteristics of the coupler structure to enhance directivity. The coupling aperture dimensions, position, and orientation are precisely designed to maximize the coupling of forward waves while minimizing the coupling of reverse waves. This local optimization of the coupling region's geometric properties directly improves measurement precision without compromising impedance adaptability.
3Measurement precision
If signal couplers are used to detect forward and reverse traveling waves, then the measurement capability is enhanced, but the power consumption of amplifiers increases
Solution Approach 1:
The coupler samples only a portion of the total signal power traversing the waveguide, rather than requiring the full signal to be processed. By extracting a small fraction of the forward and reverse traveling waves through the coupling aperture, the system achieves adequate signal detection accuracy while significantly reducing the power burden on amplifiers and detectors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The coupler-divider provides enhanced directivity and dynamic range for waveguide-based load pull measurements, supporting accurate harmonic analysis and reduced power consumption in hybrid load pull setups, operating up to 330 GHz.
Implementation Method 1
A waveguide load pull tuner is based on a waveguide transmission line; as such it can only control a fundamental frequency
Implementation Method 2
drill holes 53, 54 of various shapes (FIGS. 6A to 6C) into the adjacent walls (FIG. 5, 7) to allow electro-magnetic coupling by 'leaking' signal energy from the main waveguide transmission line to one or more adjacent secondary transmission lines
Implementation Method 3
Signal couplers are three- or more-port devices that sample a portion of the signal power traversing from an input to an output port and deliver it to a test instrument
Implementation Method 4
The microwave tuners in particular are used to manipulate the microwave impedance conditions under which the Device Under Test—DUT is tested
Data Source
AI summary
Low loss high directivity signal coupler-dividers use two additional waveguide sections coupled using traversing holes with a main waveguide section, which carries a longitudinal slot, into which a metallic tuning probe is inserted and precisely positioned. The coupler-divider allows vector load pull and sampling a portion of the signal to amplify and inject back through the tuner section to create a compact hybrid tuner for sub-THz tuning frequencies.